The model of experimental hydrocephalus in rats will be further explored. Alternate CSF pathways will be examined after the normal CSF routes are obstructed. This experimental model will also be used to study the cerebral cortical mantle changes after reversal of severe ventriculomegaly. Compliance and resistance to CSF absorption will be measured in the cerebral ventricles and the isolated spinal cord central canal of the hydrocephalic cats. The preliminary findings of decreased impedence to CSF flow in hydrocephalus as compared to normal animals will be verified with other methods such as the constant infusion technique. A search will be made for the factors responsible for enlarged cerebral ventricles when the intraventricular pressure is in the normal range. The transport of glucose from blood to CSF will be studied in hydrocephalic cats to determine whether their choroid plexus is capable of responding to alterations in CSF volume flow. In these same animals, alterations in choroid plexus blood flow will be sought with induced changes in CSF volume flow rate.